The authors developed a simple, reliable and sensitive method for the determination of pentazocine in human solid tissues using high-performance liquid chromatography, combined with a three-step liquid-liquid extraction procedure. Levallorphan tartrate served as the internal standard. The extract was evaporated to dryness and dissolved in the mobile phase of acetonitrile/10 mM phosphate buffer (pH 4.0). The eluent was pumped at a flow rate of 0.4 ml/min through a Spherisorb Ph (2.1 mm I.D. x 150 mm) column. A fluorescence detector with excitation at 247 nm and emission at 320 nm was used. The lower limit of detection was about 0.5 ng/g. The calibration curve was linear over the concentration ranges from 1 to 500 ng/g in each tissue examined and could be determined up to at least 10.0 microg/g by means of reduction of injected volumes. Using this method, the concentrations of pentazocine could be determined in the tissues of an autopsied individual for toxicological evaluation.